Firewire connection

i've bought 2 expensive cables to be able to transfer from my camcorder to the pc but have not been able to connect because i can't find a dv entry in the pc tower available that is the 3 pin ieee 1394 wide part of the other end of my cable. what i have available there is too big for that cable. and this is a new pc, lenovo that i bought last year. is there any mistake that I'm doing or something that i have to do and don't know. thanks